Close filehandles on connection reaping

- I thought this is done automatically through garbage collection, but I
think as the channel is still assigned in the asyncore map, it needs
to be done manually. Basically filehandle limit exceeded and it
crashed

src/network/connectionpool.py

@@ -111,6 +111,7 @@ class BMConnectionPool(object):
                     del self.inboundConnections[connection.destination.host]
                 except KeyError:
                     pass
+        connection.close()
 
     def getListeningIP(self):
         if BMConfigParser().safeGet("bitmessagesettings", "onionhostname").endswith(".onion"):